Audience response system with batteryless response units

ABSTRACT

A wireless response system and method of receiving user input selections at a base station includes distributing a plurality of response units to users. The response units wirelessly communicate with the base station in order to retrieve user responses received by the response units. Each of the response units has a user input device that is configured to receiving user input selections, a controller that is responsive to the user input device to process user inputs and to communicate responses wirelessly to the base station and a power supply having a super capacitor. The super capacitor is charged with a wireless-charging circuit and current is supplied from the super capacitor to the controller. Current supplied to the controller is controlled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. provisional patentapplication Ser. No. 61/570,569, filed on Dec. 14, 2011, and U.S.provisional patent application Ser. No. 61/708,171, filed on Oct. 1,2012, the disclosures of which are hereby incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

The present invention is directed to a portable electronic device and,in particular, to a wireless audience response system and method forwirelessly receiving user selections at a base station and, moreparticularly, to a wireless response system in which the response unitsare powered without a battery.

The use of chemical reaction batteries have proliferated along with theproliferation of wireless electronic devices. Such batteries createenvironmental concerns because they are often disposed in landfillswhere their chemicals can leach into ground water.

SUMMARY OF THE INVENTION

The present invention is directed to a portable electronic device, suchas an audience response system and method for wirelessly receiving userselections at a base station in which the response units are poweredwith a super capacitor in lieu of a battery. This is accomplished in amanner that the super capacitor can be charged wirelessly, such as byinductive coupling, in a manner that avoids difficulties associated withsuch technique.

A portable electronic device and method, according to an aspect of theinvention, includes a controller and a power supply having a supercapacitor. The super capacitor is charged with a wireless-chargingcircuit and current is supplied from the super capacitor to thecontroller. Current supplied to the controller is controlled. In certainembodiments, current supplied to the controller is limited in a mannerthat allows the super capacitor to acquire sufficient charge from thewireless charger to operate the controller. In certain embodimentscurrent is withheld from the controller until operation of an event.

A wireless response system and method of receiving user input selectionsat a base station, according to an aspect of the invention, includesdistributing a plurality of response units to users. The response unitswirelessly communicate with the base station in order to retrieve userresponses received by the response units. Each of the response units hasa user input device that is configured to receiving user inputselections, a controller that is responsive to the user input device toprocess user inputs and to communicate responses wirelessly to the basestation and a power supply having a super capacitor. The super capacitoris charged with a wireless-charging circuit and current is supplied fromthe super capacitor to the controller. Current supplied to thecontroller is controlled. For example, current supplied to thecontroller may be limited in a manner that allows the super capacitor toacquire sufficient charge from the wireless charger to operate thecontroller.

The wireless-charging circuit may include a pickup coil. The chargingcircuit may further include a resonance capacitor combined with the coilthereby defining a resonance circuit. The resonance circuit may resonateat a low frequency, such as at a frequency that is below approximately100 kilohertz, at a frequency that is below approximately 50 kilohertzand, in particular, at a frequency that is at approximately 38kilohertz. The charge circuit may include a voltage multiplier.

A load regulator may be provided that is configured to substantiallywithhold power from the controller until occurrence of an event, such asuser actuation of the user input device. The load regulator may be inthe form of a power impulse circuit that is configured to apply anoutput voltage to the controller for a limited period of time. Theoutput voltage may be applied upon occurrence of the event. The powerimpulse circuit may include a voltage regulator and a trigger thatenables the voltage regulator to apply the output voltage to thecontroller. The trigger may enable the voltage regulator for a limitedperiod of time upon an event, namely, actuation of the user inputdevice. The trigger may be in the form of a one-shot circuit. Thevoltage regulator may be a low drop-out voltage regulator.

The load regulator may be a voltage detecting a power source that isadapted to withhold power from the controller until the voltage on thesuper capacitor reaches a particular level. The power source may beconfigured to supply power to the controller when the voltage on thesuper capacitor reaches the particular level and continues to supplypower to the controller even when the voltage on the super capacitordecreases below the particular level. The power source may be a voltageregulator, such as a low drop-out voltage regulator.

The controller may be programmed to respond to an application of powerto the controller by entering a quiescent mode. The controller may beprogrammed to stay in a reset mode until the voltage on the supercapacitor reaches a particular level. The controller may be programmedto respond to the voltage on the super capacitor reaching the particularlevel by configuring inputs and outputs of the controller and enteringthe quiescent mode. The controller may be programmed to awake from thequiescent mode in response to the operation of the user input device.

A wireless charging station may be configured to inductively coupleelectrical energy to the wireless-charging circuit. The wirelesscharging station may include a charging coil and a coil-driving circuit.The charging coil may be configured to inductively couple with aplurality of response units. The coil may include one or more loops thatare configured to at least partially surround the plurality of responseunits. The loop(s) may completely surround the plurality of responseunits.

The coil-driving circuit may include a resonance circuit incorporatingthe coil. The coil-driving circuit may include a pair of electricalseries connected field-effect transistors and a transistor drivecircuit. The transistor drive circuit may ensure that only one of thetransistors is conducting at a time. The transistor drive circuit mayprovide dead time during which neither of the transistors is conductingbetween intervals when one of the transistors is conducting. The coildriving circuit may include an auto-tuning circuit that regulatesvoltage across the charging coil by modifying the frequency of the coildriving circuit. The coil driving circuit may include an error detectioncircuit that determines that the auto-tuning circuit has failed toachieve regulation. The error detection circuit may monitor voltageacross the charging coil and resets the auto-tuning circuit if thevoltage across the charging coil is below a threshold.

A wireless response system and method of receiving user input selectionsat a base station, according to another aspect of the invention,includes a base station and a plurality of response units. The responseunits are adapted to wirelessly communicate with the base station inorder to retrieve user responses received by the response units. Each ofsaid response units has a user input device that is adapted to receivinguser input selections, a controller that is responsive to the user inputdevice to process user inputs and to communicate responses wirelessly tothe base station and a power supply that is adapted to supply power tooperate the controller. The power supply includes a super capacitor anda wireless-charging circuit that is adapted to charge the supercapacitor. The wireless-charging circuit is adapted to supply a currentto charge the super capacitor. A power impulse circuit is adapted toapply an output voltage to the controller upon operation of the userinput device.

The power impulse circuit may apply an output voltage to the controllerfor a limited period of time upon operation of the user input device.The power impulse circuit may include a voltage regulator and a trigger.The trigger enables the voltage regulator to apply the output voltage tothe controller. The trigger may enable the voltage regulator for alimited period of time upon actuation of the user input device. Thevoltage regulator may be a low drop-out voltage regulator. The triggermay be a one-shot circuit.

While described as embodied in an audience response system, certainaspects of the invention may be applied to various portable electronicdevices, such as cell phones, digital assistants, remote controllers,real-time locating systems, and the like. These and other objects,advantages and features of this invention will become apparent uponreview of the following specification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an audience response system, according toan embodiment of the invention;

FIG. 2 is a block diagram of a response unit;

FIG. 3 is a partial electronic schematic diagram of the response unit inFIG. 2;

FIG. 4 is a more complete electronic schematic diagram of the responseunit in FIG. 2, including a microprocessor;

FIG. 5 is an electronic schematic diagram of a wireless transceiveruseful with the response unit in FIG. 2;

FIG. 6 is a block diagram of an alternative embodiment of a responseunit;

FIG. 7 is a partial electronic schematic diagram of the response unit inFIG. 6;

FIG. 8 is a more complete electronic schematic diagram of the responseunit in FIG. 6;

FIG. 9 is a block diagram of another alternative embodiment of aresponse unit;

FIG. 10 is a block diagram of yet another alternative embodiment of aresponse unit;

FIG. 11 is a flowchart of a computer program useful with the responseunit in FIG. 10;

FIGS. 12 a-12 c is a diagram of alternative coil layouts for a wirelesscharging station; FIG. 13 is an exploded perspective view of thewireless charging station illustrated in FIG. 12 a;

FIG. 14 is a perspective view of the wireless charging stationillustrated in FIG. 13 loaded with response units;

FIG. 15 is the same view as FIG. 14 with the auxiliary cradle in a useposition;

FIG. 16 is an electronic schematic diagram of a wireless chargingstation charge circuit;

FIG. 17 is a block diagram of an alternative embodiment of a wirelesscharging station charge circuit; and

FIG. 18 is an electronic schematic diagram of the wireless chargingstation charge circuit in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and the illustrative embodiments depictedtherein, a wireless response system 15 includes a base station 16 and aplurality of response units, or keypads, 18 that are in wirelesscommunication with base station 16 in order to retrieve user responsesreceived by the response units (FIG. 1). Response system 15 operatesaccording to the principles disclosed in commonly assigned U.S. Pat.Nos. 5,379,213; 5,724,357; Re. 35,449; 6,021,119; 6,665,000; 7,277,671;7,008,027; 7,599,703; 7,746,820; 7,747,261; 8,223,709 and 8,254,310 andU.S. Patent Application Publication Nos. 2003/0153347 A1; 2007/0064902A1; 2003/0153321 A1; 2002/0143415 A1; 2003/0236891 A1; 2008/0316953 A1;2009/0040183 A1; 20100061282A1; 2010/0087139 A1; 2010/0105331 A1 and2007/0042724 A1, the disclosures of which are hereby collectivelyincorporated herein by reference.

Base station 16 includes a base station controller 20 made up of amicrocontroller, or microprocessor, 21 and a radio, or wirelesstransceiver, 22 that is connected with an antenna 24 to transmit andreceive wireless communication signals. Each response unit 18 has a userinput device 28, such as a touch screen or touch pad, that is adapted toreceive user input selections, a controller 30 made up of amicrocontroller or microcomputer 32 and radio, or wireless transceiver,34 that is connected with an antenna 36 to wirelessly communicate withbase station 16. Controller 30 is responsive to user input device 28 toprocess user inputs and to communicate responses wirelessly to basestation 16. Each response unit 18 further includes a power supply 38that is adapted to supply power to operate the response unit includingcontroller 30. Power supply 38 includes a super capacitor, also known asan ultra capacitor, 40 and a wireless-charging circuit 42 that isadapted to charge super capacitor 40 from a wireless charging station90, not shown in FIG. 1. Wireless-charging circuit 42 is configured tosupply a current to charge super capacitor 40 and super capacitor 40 isconfigured to provide the sole power source for controller 30. As willbe described in more detail below, response unit controller 30 isconfigured to limit the current that is drawn from super capacitor 40 ina manner that allows super capacitor 40 to acquire a sufficient chargefrom wireless-charging circuit 42 to operate controller 30. In theillustrated embodiment, super capacitor 40 has a capacitance value of0.1 farads, but other values may be used.

In the illustrated embodiments, wireless-charging circuit 42 includes apickup coil 44 and a resonance capacitor 46 that is combined with coil44 to define a resonance circuit 43. Resonance circuit 43 resonates at alow frequency, such as at a frequency that is below approximately 100kilohertz and even below approximately 50 kilohertz. In the illustratedembodiments, resonance circuit 43 resonates at a frequency that is atapproximately 38 kilohertz. This has the advantage of resonating at afrequency that does not generally interfere with other wirelesscommunication devices. This may be accomplished by resonance circuit 43having a high Q value. This, in turn, is accomplished by pickup coil 44being a high inductance, low current coil. In the illustratedembodiments, pickup coil 44 is a transponder coil that is of the typeused in radio frequency identification (RFID) devices and has aninductance of greater than 5 millihenry. In the illustrated embodiments,coil 44 has an inductance of 7.2 millihenry. Such coil is commerciallyavailable as an RFID transponder coil Model 5315TC from Coilcraft, Inc.in Cary, Ill. Wireless charge circuit 42 includes a rectifier 48.Rectifier 48 is in the form of a voltage multiplier, such as a voltagedoubler. Such voltage multiplier provides a higher voltage, such as 6volts peak-to-peak, on super capacitor 40, but requires a longer chargetime.

In an embodiment illustrated in FIGS. 2-5, power supply 38 includes aload regulator 50. Load regulator 50 substantially withholds power fromcontroller 30 until the occurrence of an event. Load regulator 50 mayinclude a power impulse circuit 52 that applies an output voltage tocontroller 30 for a limited period of time upon occurrence of the event.In the illustrated embodiment in FIG. 3, load regulator 50 includes avoltage regulator U1 and power impulse circuit 52 includes a triggerthat enables voltage regulator U1 to apply its output voltage tocontroller 30 for a limited period of time upon actuation of user inputdevice 28. More particularly, power impulse circuit 52 is in the form ofa one-shot circuit including a transistor Q1 connected with the enablinginput of regulator U1 through a capacitor C10. A field-effect transistorU3 couples the enable input of regulator U1 with its output. The base oftransistor Q1 is connected the switches of user input device 28 througha diode set D3-D7.

Load regulator 50 operates as follows. When response unit 15 is broughtinto inductive coupling range with wireless charging station 90, theenabling input of voltage regulator U1 is disabled, thus preventingvoltage regulator U1 from producing a voltage Vdd supplied to controller30. This removes all but a trickle load from super capacitor 40, thusallowing a charge to build up on the super capacitor fromwireless-charging circuit 42. This condition continues until an operatoractuates one of the switches of user input device 28. The switchactuation pulls the base of transistor Q1 low, thus causing the switchto turn on pulling the enable input of voltage regulator U1 to a higherstate which enables the voltage regulator to produce an output voltageVdd. This voltage is supplied to microprocessor 32. Microprocessor 32responds to the application of power by powering up. Once voltageregulator U1 produces an output voltage, FET U3 latches its enable linehigh until capacitor C9 charges up sufficiently to turn FET U3 off. Theresult is that power is supplied to controller 30 for a momentary periodof time upon the actuation of user input device 28 by a user. The timeperiod is set to be sufficient for controller 30 to process the userinput and transfer the user input to base station 16. In the illustratedembodiment, the impulse time interval of power impulse circuit 52 is 250milliseconds, but other time may be selected.

An advantage of load regulator 50 is that it substantially completelyisolates response unit controller 30 from super capacitor 40 until auser presses a key on user input device 28. This isolates controller 30from the super capacitor 40 to allow the charge on the super capacitorto build sufficiently to operate controller 30. It also removes the loadfrom the super capacitor when the user is not operating input device 28.It also removes the power to controller 30 after the period of time setby one-shot circuit 58 should the user hold the key down for longer thanthe period set by the one-shot circuit. It should be understood thatcertain of the advantages of load regulator 50 can be achieved byvariations thereof. For example, such load regulator may be in the formof mechanically isolating the supply voltage from controller 30 unless auser presses a switch of user input device 28. However, the use of loadregulator 50 with power impulse circuit 52 has the advantage of notallowing ongoing drain on the super capacitor should the user hold theswitch in the pressed state for a long period of time.

In the illustrated embodiment, voltage regulator U1 is a low drop-outvoltage regulator (LDO). Such LDO has the advantage of a minimaldecrease in voltage by the LDO such that its output voltage is closer toits input.

An alternative embodiment of a wireless response system includes aresponse unit 118 having a power supply 138 including a load regulator150 in the form of a voltage detecting voltage supply 60 that is adaptedto withhold power from controller 30 until the voltage on supercapacitor 40 reaches a particular level (FIGS. 6-8). Load regulator 150also has hysteresis and thereby is configured to continue to supplypower to controller 30 when voltage on the super capacitor decreasesbelow the particular level. Load regulator 150 includes a voltageregulator U2 that, in the illustrated embodiment, is a low drop-outvoltage regulator with an enabling line having hysteresis. The enableline to voltage regulator U2 is connected with a voltage divider formedby resisters R12 and R13 connected in parallel with super capacitor 40.In this manner, while super capacitor 40 is being charged, the voltageacross the capacitor starts by being too low to activate enabling inputto voltage regulator U2. As a result, voltage regulator U2 does notproduce a voltage Vdd supplied to microprocessor 32. Once voltage acrosssuper capacitor 40 rises sufficiently to enable voltage regulator U2,voltage Vdd is supplied to controller 30. In this manner, the supercapacitor is allowed to accumulate a charge sufficient to power thecontroller before the controller is allowed to operate. However, oncethe controller is powered, it is allowed to continue to operate evenafter the level of Vdd drops below that initially supplied to thecontroller because of the hysteresis of voltage regulator U2. Also,microprocessor 32 is programmed in a manner that, once themicroprocessor is initially powered, it wakes up only long enough toplace itself in a quiescent mode or sleep mode. Therefore, it is notnecessary for the microprocessor to wait for a period of non-use beforeentering the sleep mode. Once in the sleep mode, microprocessor 32remains in the sleep mode until interrupted, such as by the operation ofuser input device 28, or the like. Microcomputer 32 draws less currentin its sleep mode than is produced by power supply 38. In this manner,super capacitor 40 can continue to accumulate a charge even after thevoltage across the super capacitor is sufficient to produce voltage Vddand activate microprocessor 32. Also, where super capacitor 40 is notbeing charged, the accumulated charge on the super capacitor isconserved when microprocessor 32 is in a sleep mode. This allows longeroperation of the response unit between charges.

In another embodiment, a wireless response system includes a responseunit 218 in which a controller 230 includes a microprocessor and radiocombined in a single integrated circuit (FIG. 9). Otherwise, responseunit 218 is similar to response unit 118.

In yet another embodiment, a wireless response system includes aresponse unit 318 having a controller 330 that is programmed to limitthe current that is drawn from super capacitor 40 in a manner thatallows super capacitor 40 to acquire a sufficient charge fromwireless-charging circuit 42 to operate controller 330 (FIGS. 10 and11). In this embodiment, controller 330 is programmed to respond to anapplication of power to said controller 330 by entering a quiescentmode. Thus, once voltage across super capacitor 40 is high enough topower controller 330, the super capacitor is able to continue toaccumulate a charge because the controller will be in a quiescent, orsleep, mode. This is accomplished in the illustrated embodiment bycontroller 330 being programmed with a computer program 65 which startsat 66 with controller 330 staying in a reset mode until it is determinedat 68 that voltage on super capacitor 40 reaches a particular level,such as 2 VDC, for example. When controller 330 is in such reset mode,the current draw by the controller is less than that applied by chargingcircuit 42 to charge super capacitor 40. When it is determined at 68that the voltage on super capacitor 40 reaches the particular level, thecontroller is taken out of the reset mode at 70 by configuring inputsand outputs thereof at 76, 78 and 80. During such steps, the controllercan be run at a slower speed (72) to further conserve power or a fasterspeed (74) to configure the controller quicker but at a higher rate ofpower consumption. Once controller 30 is configured (76, 78, 80) program65 enables controller 30 at 82 to be able to wake up upon receiving auser input from user input device 28. Program 65 then places controller30 in a quiescent mode at 84. Program 65 then waits receipt of a userinput at 86. When a user input is received, program 65 then runs themain program at 88. The main program processes the user input, whichcauses the user input to be wirelessly transferred to base station 16and go back to sleep.

Wireless response system 15 includes a wireless charging station, ordevice, 90, 190, 290 that is configured to inductively couple electricalenergy to charging circuit 42 by way of pickup coil 44. Such wirelesscharging station includes one or more charging coils 92, 192, 292 and acoil-driving circuit 94, 194. In the embodiments illustrated in FIGS. 12a and 12 c, respective charging coils 92, 292 are configured toinductively couple with a plurality of response units 18. This may beaccomplished by charging coils 92, 192 being made up of one or moreloops of an electrical conductor that at least partially surrounds theresponse units. In FIG. 12 a, one conductor loop completely surrounds aplurality of response units. In FIG. 12 c a plurality of charging coils292 each includes an electrical conductor loop that partially surroundmultiple response units 18. In an embodiment illustrated in FIGS. 12 b,a charging coil 192 is provided for each response unit. It is understoodthat a non-magnetic housing 93 is provided to support the multipleresponse units in the wireless charging station.

Referring to FIGS. 13-15, charging station 90 includes a plurality ofcoil support blocks 95 made of an electrically insulating material thatprovide an interference fit between charging coil 92 and a base 97 whenbase 97 is attached to housing 93. In particular, blocks 95 are sized topress coil 92 into a crevice in housing 93 when base 97 is attached tothe housing. A circuit board 98 that contains charge circuit 94 isattached inside of housing 93. Coil 92 surrounds an opening 99 in whichresponse units 18 are positioned for charging of super capacitor 40.

Charging station 90 may further include one or more auxiliary cradles100 that are capable of supporting one or more response units 18, asseen in FIG. 14. With cradle 100 supported from a side of housing 93, asseen in FIG. 15, the response units 18 positioned in the cradle will bemagnetically coupled to coil 92 and thereby be wirelessly charged in asimilar manner as response units 18 positioned in opening 99. However,the electrical conductor or coil 92 will run adjacent to, not surround,response units positioned in cradle 100. An additional cradle 101 may bedefined at an end portion of housing 93. Cradle 101 is defined to holdbase station 16. Base station 16 is configured to interface with a UBSport of personal computer 26. Since base station 16 receives electricalpower from the UBS port, it does not have a super capacitor and issufficiently spaced from coil 92 so any electrical charge present atcradle 101 is not coupled to base station 16 from coil 92 when the basestation is in cradle 101 because there is no circuitry in base station16 to respond to the field.

Coil-driving circuit 94 is a resonance circuit including coil 92, 192 or292. Coil-driving circuit 94 includes one or more resonance capacitorsC6, C7 and a pair of electrical series connected field-effecttransistors U3, U5 and a transistor drive circuit 96. Transistor drivecircuit 96 ensures that only one of transistors U3, U5 is conducting ata time in order to ensure that there is never a direct short circuitthough transistors U3 and U5. This is accomplished by transistor drivecircuit 96 providing dead time during which neither of transistors U3,U5 is conducting between intervals when one of transistors U3, U5 isconducting. If more than one charging coil is used, they may be drivenfrom a common set of transistors U3, U5, or a separate set oftransistors U3, U5 and a resonance capacitor may be provided for eachcoil.

In an alternative embodiment, a coil-driving circuit 194 includes adrive circuit 196 to drive electrically series connected field-effecttransistor (FET) U3, U5 which are connected through resonance capacitorsC6, C7 with charging coil 92, 192 or 292. The connection betweencapacitors C6, C7 and the charging coil provides an input 102 to anauto-tuning circuit 103 which has an output 104 that is supplied todriver circuit 196. Auto-tuning circuit 103 responds to the peak voltagelevel at its input 102 by producing a variable frequency signal on itsoutput 104 that is supplied to driver 196. Auto-tuning circuit 103increases the frequency of the signal on output 104 when thepeak-to-peak voltage level at input 102 decreases below a set voltagelevel. Driver 196 drives FETs U3, U5 at the same frequency as output 104which increases the peak-to-peak voltage level across coil 92, 192, 292.Thus, auto-tuning circuit 103 acts as a feed-back loop to maintain aconstant voltage across the charging coil.

If a large piece of metal, such as a scissors, stapler, or the like, isinadvertently placed in opening 99, or something else causes anexcessive drain on charging coil 92, 192, 292, the frequency of output104 may be operated at a peak level by auto-tuning circuit 103 anddriving circuit 194 may still not be able to achieve regulation. Anerror-detection circuit 105 may be provided to supervise auto-tuningcircuit. Error-detection circuit 105 responds to input 102 and producesan output 106 that is supplied to auto-tuning circuit 103. Output 106 iscapable of resetting the auto-tuning circuit if input 102 drops below athreshold peak voltage level. Error-detection circuit 105 then allows anamount of time, such as 0.5 seconds, for auto-tuning circuit 103 toachieve regulation. However a longer or shorter period of time may bechosen. This periodic resetting of auto-tuning circuit 103 by errordetection circuit 105 allows auto-tuning circuit 103 to attempt toachieve regulation of the voltage level across the charging coil. Ifregulation of voltage at input 102 is still not achieved after about 0.5seconds, error detection circuit 105 once again resets auto-tuningcircuit 103. If the metallic object is removed from opening 99,auto-tuning circuit 103 will once again achieve regulation of thevoltage across the charging coil.

In the illustrated embodiment, auto-tuning circuit 103 includes acomparator U8A that compares the voltage at input 102 with a referencevoltage. If it drops below the reference voltage then a transistor Q3 isswitched which sinks a set input on a voltage to frequency converter U7which increases the frequency of its output. The output of U7 issupplied to a transistor Q1 which provides input 104 to FET driver 164.Driver 164 drives FETs U3, U5 at a higher frequency which should raisethe voltage level across the charging coil. Once comparator U8Adetermines that the voltage level on input 102 exceeds the threshold setfor it, the frequency at which FETs U3, U5 are driven is decreased. Thisresults in small adjustments to the frequency at which FETs Q3 and Q5are driven.

Error detection circuit 105 also has a comparator U8B that compares thevoltage level on input 102 against a reference. If it drops below alevel of the reference, a transistor Q4 applies a voltage to a voltageto frequency circuit U9 which produces a low frequency output 106 thatis supplied to a transistor Q2. When the voltage on output 106 reaches athreshold, it causes transistor Q2 to conduct which discharges capacitorC16 at the base of transistor Q3. This claims Q3 off until capacitor C16charges through resistor R17. In this manner, error detection circuit105 resets auto-tuning circuit 103, should it fail to achieveregulation.

While the foregoing description describes several embodiments of thepresent invention, it will be understood by those skilled in the artthat variations and modifications to these embodiments may be madewithout departing from the spirit and scope of the invention, as definedin the claims below. For example, rather than using inductively coupledcoils for supplying electrical energy to charge the super capacitor, itmay be possible to use a photon-coupled charger. In such a charger,light generated by LED's in a charging station can be coupled to LED'sin the portable device to generate current to charge the supercapacitor. The present invention encompasses all combinations of variousembodiments or aspects of the invention described herein. It isunderstood that any and all embodiments of the present invention may betaken in conjunction with any other embodiment to describe additionalembodiments of the present invention. Furthermore, any elements of anembodiment may be combined with any and all other elements of any of theembodiments to describe additional embodiments.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A wireless responsesystem, comprising: a base station and a plurality of response units,said response units wirelessly communicating with said base station inorder to retrieve user responses received by said response units; eachof said response units having a user input device that is adapted toreceiving user input selections, a controller that is responsive to saiduser input device to process user inputs and to communicate responseswirelessly to said base station and a power supply that is adapted tosupply power to operate said controller; wherein said power supplycomprises a super capacitor and a wireless-charging circuit that isadapted to charge said super capacitor; wherein said wireless-chargingcircuit is adapted to supply a current to charge said super capacitorand wherein said power supply or said controller is configured tocontrol the current that is drawn from said super capacitor.
 2. Theresponse system as claimed in claim 1 wherein said wireless-chargingcircuit comprises a pickup coil.
 3. The response system as claimed inclaim 2 wherein said charging circuit further comprises a resonancecapacitor combined with said coil thereby defining a resonance circuit.4. The response system as claimed in claim 3 wherein said resonancecircuit resonates at a low frequency.
 5. The response system as claimedin claim 4 wherein said resonance circuit resonates at a frequency thatis below approximately 100 kilohertz.
 6. The response system as claimedin claim 5 wherein said resonance circuit resonates at a frequency thatis below approximately 50 kilohertz.
 7. The response system as claimedin claim 6 wherein said resonance circuit resonates at a frequency thatis at approximately 38 kilohertz.
 8. The response system as claimed inclaim 1 wherein said charge circuit comprises a voltage multiplier. 9.The wireless response system as claimed in claim 1 including a loadregulator, said load regulator substantially withholds power from saidcontroller until occurrence of an event.
 10. The wireless responsesystem as claimed in claim 9 wherein said load regulator comprises apower impulse circuit, said power impulse circuit adapted to apply anoutput voltage to said controller upon occurrence of the event for alimited period of time.
 11. The wireless response system as claimed inclaim 10 wherein said power impulse circuit includes a voltage regulatorand a trigger, said trigger enabling said voltage regulator to apply theoutput voltage to said controller.
 12. The wireless response system asclaimed in claim 11 wherein said trigger enables said voltage regulatorfor a limited period of time upon actuation of said user input device.13. The wireless response system as claimed in claim 12 wherein saidtrigger comprises a one-shot circuit.
 14. The wireless response systemas claimed in claim 11 wherein said voltage regulator comprises a lowdrop-out voltage regulator.
 15. The wireless response system as claimedin claim 1 wherein said controller is configured to limit the currentthat is drawn from said super capacitor in a manner that allows saidsuper capacitor to acquire sufficient charge from said wireless-chargingcircuit to operate said controller.
 16. The wireless response system asclaimed in claim 15 including a voltage-detecting power source that isadapted to withhold power from said controller until voltage on saidsuper capacitor reaches a particular level.
 17. The wireless responsesystem as claimed in claim 16 wherein said power source is adapted tosupply power to said controller when voltage on said super capacitorreaches the particular level and to continue to supply power to saidcontroller when voltage on said super capacitor decreases below theparticular level.
 18. The wireless response system as claimed in claim17 wherein said power source comprises a voltage regulator.
 19. Thewireless response system as claimed in claim 18 wherein said voltageregulator comprises a low drop-out voltage regulator.
 20. The wirelessresponse system as claimed in claim 1 wherein said controller isprogrammed to respond to an application of power to said controller byentering a quiescent mode.
 21. The wireless response system as claimedin claim 1 wherein said controller is programmed to stay in a reset modeuntil voltage on said super capacitor reaches a particular level. 22.The wireless response system as claimed in claim 21 wherein saidcontroller is programmed to respond to the voltage on said supercapacitor reaching the particular level by configuring inputs andoutputs thereof and entering the quiescent mode.
 23. The wirelessresponse system as claimed in claim 22 wherein said controller isprogrammed to awake from the quiescent mode in response to the operationof said user input device.
 24. The wireless response system as claimedin claim 1 including a wireless charging station, said wireless chargingstation adapted to inductively couple electrical energy to said chargingcircuit.
 25. The wireless response system as claimed in claim 24 whereinsaid coil-driving circuit is a resonance circuit with said coil.
 26. Thewireless response system as claimed in claim 24 wherein said wirelesscharging station comprises a charging coil and a coil-driving circuit.27. The wireless response system as claimed in claim 26 wherein saidcharging coil is configured to inductively couple with a plurality ofsaid response units.
 28. The wireless response system as claimed inclaim 27 wherein said charging coil comprises at least one loop of anelectrical conductor that is configured to at least partially surroundsaid plurality of said response units.
 29. The wireless response systemas claimed in claim 28 wherein said at least one loop of an electricalconductor completely surrounds said plurality of said response units.30. The wireless response system as claimed in claim 26 wherein saidcoil-driving circuit comprises a pair of electrical series connectedfield-effect transistors and a transistor drive circuit, said transistordrive circuit ensuring only one of said transistors is conducting at atime.
 31. The wireless response system as claimed in claim 30 whereinsaid transistor drive circuit provides dead time during which neither ofsaid transistors is conducting between intervals when one of saidtransistors is conducting.
 32. The wireless response system as claimedin claim 26 wherein said coil driving circuit comprises an auto-tuningcircuit that regulates voltage across said charging coil by modifyingthe frequency of the coil driving circuit.
 33. The wireless responsesystem as claimed in claim 32 wherein said coil driving circuit includesan error detection circuit that determines that said auto-tuning circuithas failed to achieve regulation.
 34. The wireless response system asclaimed in claim 33 wherein said error detection circuit monitorsvoltage across said charging coil and resets said auto-tuning circuit ifthe voltage across said charging coil is below a threshold.
 35. A methodof wirelessly receiving user input selections at a base station, saidmethod comprising: distributing a plurality of response units to users,said response units wirelessly communicating with the base station inorder to retrieve user responses received by said response units, eachof said response units having a user input device that is adapted toreceiving user input selections, a controller that is responsive to saiduser input device to process user inputs and to communicate responseswirelessly to said base station and a power supply comprising a supercapacitor; and charging said super capacitor with a wireless-chargingcircuit and supplying current from said super capacitor to saidcontroller including controlling current supplied to said controller.36. A wireless response system, comprising: a base station and aplurality of response units, said response units wirelesslycommunicating with said base station in order to retrieve user responsesreceived by said response units; each of said response units having auser input device that is adapted to receiving user input selections, acontroller that is responsive to said user input device to process userinputs and to communicate responses wirelessly to said base station anda power supply that is adapted to supply power to operate saidcontroller; wherein said power supply comprises a super capacitor and awireless-charging circuit that is adapted to charge said supercapacitor, wherein said wireless-charging circuit is adapted to supply acurrent to charge said super capacitor; and a power impulse circuitadapted to apply an output voltage to said controller upon operation ofsaid user input device.
 37. The wireless response system as claimed inclaim 36 wherein said power impulse circuit applies an output voltage tosaid controller for a limited period of time upon operation of said userinput device.
 38. The wireless response system as claimed in claim 37wherein said power impulse circuit includes a voltage regulator and atrigger, said trigger enabling said voltage regulator to apply theoutput voltage to said controller.
 39. The wireless response system asclaimed in claim 38 wherein said trigger enables said voltage regulatorfor a limited period of time upon actuation of said user input device.40. The wireless response system as claimed in claim 39 wherein saidvoltage regulator comprises a low drop-out voltage regulator.
 41. Thewireless response system as claimed in claim 38 wherein said triggercomprises a one-shot circuit.